Kuliah Sistem Pakar Pertemuan V “Representasi Pengetahuan”

Proses Rekayasa Pengetahuan (Knowledge Engineering Process) Validasi Pengetahuan Sumber Pengetahuan Akuisisi Pengetahuan Basis Pengetahuan Representasi Pengetahuan Pengkodean Justifikasi Penjelasan Inferensi

Knowledge Representation Knowledge Representation is concerned with storing large bodies of useful information in a symbolic format. Most commercial ES are rule-based systems where the information is stored as rules. Frames may also be used to complement rule-based systems.

Tipe-tipe Pengetahuan berdasar Sumber Deep Knowledge (formal knowledge) Shallow /Surface Knowledge (non formal knowledge)

Penjelasan ……… Deep knowledge atau pengetahuan formal, pengetahuan bersifat umum yang terdapat dalam sumber pengetahuan tertentu (buku, jurnal, buletin ilmiah dsb) dan dapat diterapkan dalam tugas maupun kondisi berbeda. Shallow knowledge atau pengetahuan non formal, pengetahuan-pengetahuan praktis dalam bidang tertentu yang diperoleh seorang pakar pengalamannya pada bidang dalam jangka waktu cukup lama.

Tipe-tipe Pengetahuan berdasar Cara Merepresentasikan Pengetahuan Heuristik Pengetahuan Prosedural Pengetahuan Deklaratif

Representasi Pengetahuan Propotional Logic (logika proposional) Semantic Network (jaringan semantik) Script, List, Table, dan Tree Object, Attribute, dan Values Production Rule (kaidah produksi) Frame

Representation in Logic and Other Schemas General form of any logical process Inputs (Premises) Premises used by the logical process to create the output, consisting of conclusions (inferences) Facts known true can be used to derive new facts that also must be true

Two Basic Forms of Computational Logic Propositional logic (or propositional calculus) Predicate logic (or predicate calculus)

Symbols represent propositions, premises or conclusions Statement: A = The mail carrier comes Monday through Friday. Statement: B = Today is Sunday. Conclusion: C = The mail carrier will not come today. Propositional logic: limited in representing real-world knowledge

Propositional Logic A proposition is a statement that is either true or false Once known, it becomes a premise that can be used to derive new propositions or inferences Rules are used to determine the truth (T) or falsity (F) of the new proposition

Propotional Logic Logic dapat digunakan untuk melakukan penalaran :  Contoh : Pernyataan A = Pak Pos datang hari Senin sampai Sabtu Pernyataan B = Hari ini hari Minggu Kesimpulan C = Pak Pos tidak akan datang hari ini Input Premise atau Fakta-Fakta Output Inferensi atau Konklusi Proses Logik

(Note - the period “.” is part of the statement) Predicate Calculus Predicate logic breaks a statement down into component parts, an object, object characteristic or some object assertion Predicate calculus uses variables and functions of variables in a symbolic logic statement Predicate calculus is the basis for Prolog (PROgramming in LOGic) Prolog Statement Examples comes_on(mail_carrier, monday). likes(jay, chocolate). (Note - the period “.” is part of the statement)

Jaringan Semantik Merupakan gambaran pengetahuan berbentuk grafis dan menunjukkan hubungan antar berbagai obyek. Obyek, berupa benda atau peristiwa Nodes Obyek Arc (Link) Keterhubungan (Relationships) * is a * has a

Contoh : 1) Human Is a Being Boy Is a Is a Needs Goes to Woman Joe School Is a Food Has a child Kay

2) SAM MERCEDES BENZ JERMAN PERAK MOBIL GOLF OLAH- RAGA WAKIL PRESDIR ACME AJAX KAY LAKI- LAKI MANUSIA MAKANAN PEREM- PUAN ANAK JOE SEKOLAH pergi ke adalah perlu mempunyai anak kawin dengan punya jabatan bekerja di perusahaan bermain merk buatan berwarna

Script, List, Table, dan Tree

Scripts Contoh : Script “Ujian Akhir Semester” SCRIPT, skema representasi pengetahuan yang menggambarkan urutan dari kejadian. Elemen-elemen script terdiri dari : Elements include Entry Conditions Props Roles Tracks Scenes Contoh : Script “Ujian Akhir Semester”

List LIST, daftar tertulis dari item-item yang saling berhubungan. Umumnya digunakan untuk merepresentasikan hirarki pengetahuan dimana suatu obyek dikelompokan, dikategorikan sesuai dengan Rank or Relationship Contoh : berupa daftar orang yang anda kenal, benda-benda yang harus dibeli di pasar swalayan, hal-hal yang harus dilakukan minggu ini, atau produk-produk dalam suatu katalog.

Decision Tabel DECISION TABLE, pengetahuan yang diatur dalam format lembar kerja atau spreadsheet, menggunakan kolom dan baris. Attribute List Conclusion List Different attribute configurations are matched against the conclusion Contoh :… ?

Decision Trees DECISION TREE, tree yang berhubungan dengan decision table namun sering digunakan dalam analisis sistem komputer (bukan sistem AI). Contoh :… ? Related to tables Similar to decision trees in decision theory Can simplify the knowledge acquisition process Knowledge diagramming is frequently more natural to experts than formal representation methods

Object, Attribute, Values OBJECT dapat berupa fisik atau konsepsi. ATTRIBUTE : ATTRIBUTE adalah karakteristik dari object. VALUES : VALUES adalah ukuran spesifik dari attribute dalam situasi tertentu

Object Attribute Values Rumah Kamar tidur 2,3,4, dsb. Warna Hijau, Putih, Coklat dsb. Diterima di Universitas Nilai Ujian masuk A, B, C atau D Pengendalian persedian Level persediaan 15, 20, 25, 35, dsb. Ukuran 3x4, 5x6, 4x5, dsb.

Production Rules PRODUCTION RULES: Production system dikembangkan oleh Newell dan Simon sebagai model dari kognisi manusia. Ide dasar dari sistem ini adalah pengetahuan digambarkan sebagai production rules dalam bentuk pasangan kondisi-aksi.

Production Rules Condition-Action Pairs IF this condition (or premise or antecedent) occurs, THEN some action (or result, or conclusion, or consequence) will (or should) occur IF the stop light is red AND you have stopped, THEN a right turn is OK

Each production rule in a knowledge base represents an autonomous chunk of expertise When combined and fed to the inference engine, the set of rules behaves synergistically Rules can be viewed as a simulation of the cognitive behavior of human experts Rules represent a model of actual human behavior

Contoh : Production Rules RULE 1 : JIKA konflik internasional mulai MAKA harga emas naik   RULE 2 : JIKA laju inflasi berkurang MAKA harga emas turun RULE 3 : JIKA konflik internasional berlangsung lebih dari tujuh hari dan JIKA konflik terjadi di Timur Tengah MAKA beli emas

Production Rules Condition-Action Pairs IF this condition (or premise or antecedent) occurs, THEN some action (or result, or conclusion, or consequence) will (or should) occur IF the stop light is red AND you have stopped, THEN a right turn is OK

Each production rule in a knowledge base represents an autonomous chunk of expertise When combined and fed to the inference engine, the set of rules behaves synergistically Rules can be viewed as a simulation of the cognitive behavior of human experts Rules represent a model of actual human behavior

Forms of Rules IF premise, THEN conclusion IF your income is high, THEN your chance of being audited by the IRS is high Conclusion, IF premise Your chance of being audited is high, IF your income is high

Inclusion of ELSE IF your income is high, OR your deductions are unusual, THEN your chance of being audited by the IRS is high, OR ELSE your chance of being audited is low More Complex Rules IF credit rating is high AND salary is more than $30,000, OR assets are more than $75,000, AND pay history is not "poor," THEN approve a loan up to $10,000, and list the loan in category "B.” Action part may have more information: THEN "approve the loan" and "refer to an agent"

Frame FRAME adalah struktur data yang berisi semua pengetahuan tentang obyek tertentu. Pengetahuan ini diatur dalam suatu struktur hirarkis khusus yang memperbolehkan diagnosis terhadap independensi pengetahuan. Frame pada dasarnya adalah aplikasi dari pemrograman berorientasi objek untuk AI dan ES. Setiap frame mendefinisikan satu objek, dan terdiri dari dua elemen : slot (menggambarkan rincian dan karakteristik obyek) dan facet.

Frames Frame: Data structure that includes all the knowledge about a particular object Knowledge organized in a hierarchy for diagnosis of knowledge independence Form of object-oriented programming for AI and ES. Each Frame Describes One Object Special Terminology

Contoh Frame Automobile Frame Class of : Transportation Name of Manufacturer : Audi Origin of Manufacturer : Germany Model : 5000 turbo Type of Car : Sedan Weight : 3000 lbs. Wheelbase : 105.8 inches Number of doors : 4 (default) Transmission : 3-speed (automatic) Number of wheels : 4 (default) Gas mileage : 22 mpg average (procedural attachment) Engine Frame Cylinder bore : 3.19 inches Cylinder stroke : 3.4 inches Compression ratio : 7.8 to 1 Fuel system : Injection with turbocharger Horsepower : 140 hp Torque : 160 ft/Lbs

Hirarki Frame (exp : Vehicle)     Vehicle Frame Train Frame Boat Frame Car Frame Airplane Frame Submarine Frame Passenger Car Frame Truck Frame Bus Frame Compact Car Frame Midsize Car Frame Toyota Corolla Frame Mitsubishi Lancer Frame Mary’s Car Frame Jan’s Car Frame

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